Initiation factor

Initiation factors (more precisely, the translation initiation factor ), proteins and protein complexes in the cells of all living organisms, which are required for efficient translation of the mRNA and have a function during the initiation of translation. Since the initiation of substantially different from that of eukaryotes, prokaryotes, proteins participating in mind must be differentiated. Mutations in the genes that encode subunits of eIF -2B complex are for a particular genetic form of leukodystrophy ( FWM ) is responsible.

Prokaryotic initiation factors

Prokaryotes have three proteins ( IF-1, IF-2 and IF -3) that initiate the translation together. They all bind to the small subunit of the ribosome. Each of these proteins has a specific function and assumes a level of initiation:

• IF-1 prevents the premature binding of the tRNA to the location of the mRNA, which is subsequently formed the A site of the ribosome.
• IF -2 is a GTPase. Please be assured that the initiator tRNA ( tRNA formyl ) binds to the start codon. The energy released by the hydrolyzation of a GTP interacts with IF-1, the small subunit of the ribosome and the initiator tRNA.
• IF -3 prevents the premature binding of the large subunit of the small. IF - 3 binds as early as possible in the small subunit, is insured so that a new translation can be initialized. It even seems to be that this factor supports the cleavage of the small and large subunit after translation.

Eukaryotic initiation factors

Eukaryotic initiation factors belong to many different protein families and have a variety of functions: the mRNA to wrest, to recognize their 5'- cap structure to regulate their binding to the ribosome to bind the initiator tRNA and to leave the complex, thus the ribosome 60S subunit can carry out the elongation.

In humans, about 45 genes are known that encode eukaryotic initiation factors. The proteins belonging to the following complexes and Families: